Loud-speaking telephone receiver



May 28, 1929. A. A. THOMAS LOUD SPEAKING TELEPHONE RECEIVE Filed May 11, 1925 Patented Ma 28; 1929.

UNITED STATES PATENT" oFFicE.

ADOLPH A. THOMAS, OF NEW YORK, N. Y., ASSIGNOR TO BRANDES LABORATORIES,

INCL, OF NEWARK, NEW JERSEY, A CORPORATION OF NEW JERSEY.

nounsrnaxme TELEPHONE ancnrvna.

rigina1 application filed December 14, 1923, Serial No. 680,597. Dividedand I 11, 1925. Serial No. 29,472.

My invention relates to telephone instruments, and its main object is to provide a loudspeaking receiver particularly adapted for use in radio reception, although not limited to this field. My invention comprises improved means for mounting the operative parts of a telephone loudspeaker in a readily accessible po: sition within an outer casing or housing, which is rigidly mounted on a stand or base and to whicha horn is connected. To the lower end of the casing within the base is secured a cap member which carries suitable magnetic mechanism adapted to operate an acoustic diaphragm within the upper casing. As a result of this novel construction and arrangement, the parts of the instrument are readily assembled and taken apart, when occasion requires,

In the construction which I prefer at the present time, the outer casing is supported.

on and connected to the base by a snug firm fit, so that the base may be removed without the use of special tools, as when it is desired .to connect the mechanism with a phonograph horn or other fixed amplifier.

The foregoing and other object-sand advantages of my invention will become clear from a detailed descript-ion'of the accompanyembodiment of my invention. In these drawings Fig. 1 is a transverse cross-section on line 11 of Fig. 2, showing a loudspeaking telephone receiver constructed in accordance with my invention; Y

Fig. 2 is a top plan view in section, approxi mately on the broken line 2-2 of Fig. 1; and Fig. 3 is a detached perspective View of the casting or cap member which directly .supports the magnetic mechanism and, in this particular instance, also the diaphragm.

' An outer casing or housing indicated as a whole by K is supported on a base or stand T of suitable construction and design. The housing K, which may be cast or molded as a single piece of any suitable material (such as bakelite, aluminum, etc.), consists of a closed upper section 1 and an open lower section 2. The upper section 1 is provided with an -integral neck 3 adapted to receivethe inner end 4 ot a suitable amplifying horn. For this purpose. the neck 3 may be made slightly cone-shaped, so as to provide a tight fit for ing drawings, which illustrate a preferred this ma filed my the horn. Between its upper and lower secoutwardly projecting annular flange 5 arranged to engage an annular, shoulder or .55 tions, the housing K is provided with an p The frictional and positive securing means thus formed by the engaging surfaces of base T and housing K is suflicient to hold the housing securely on its'support-' mg base, and no separate fastening devices are necessary in this referred construction.

To remove the casing and all parts carried thereby, it is only necessary to separate it from the base, which is easily done without the use of. tools. The instrument may be used without the stand T, as when it is de,-:

sired to connect it with a phonograph horn in a, cabinet. In that case, the neck or extension'3 is shaped to fit over the outer end of the tone arm or whatever acoustic connection with the horn may be used.

To the lower section 2 of casing'K is se-' cured a casting indicated as a whole ;by B,

as 'best'shown in Fig. 3. This casting, which may be called a second housing, ill-"this 'instance comprises a circular base section 9, a

ring'lO, and connecting posts 11. If desired, these parts may bemade separate and rigidly secured together, but it is preferable to mold or cast them in a single rigid piece out of a suitable non-magnetic material, such as aluminum, bakelite, andthe like.. So it will be understood that when I refer to the part B as a-casting, I use the term merely for convenience.

On the base section 9 of the supporting member B is mounted any practical form of magnetic mechanism suitable for operating an acbustic diaphragm. Merely by .way of example, I have shown a pair of permanentgap 19. The two magnets constitute in effect' a single magnet with a bifurcated northpole -17 and 'abifurcat'ed south pole 16-18 San yice versa).' Although I have referred t the magnets 12 and-13 as permanent magnets, theymayobviously bein the form of electromagnets.

The pole pieces 15.-17 and 16 18 are conv nected byiron cores on which are mounted coils Qladapted to be connected in a suitable telephone circuit in which the current varies in accordance with sound waves intended to be reproduced by the receiver. Thesejcoils are connected in series and'thus 1n efiect con- I stitute a single coil, whichI may conveniently call the telephone coil. ietween the tips or free ends of pole pieces 15-17 and 16 18 is mounted an armature A,

which may simply be a short flat bar of iron 1 of the rig z dependingupon the relative arrangement andsize of the pole pieces. The

armature is operatively supportedin any practical way. In the drawings I have shown.

bracket 22 is firmly mounted on the base sec--' tion 9 of housing B in any suitable way, as .by means of screws or bolts 23. Any other practical mounting for the armature may be used. I

The lower end of easing K is screw-thread-;

ed to receive the screw-threaded shoulder 24 of casing B, which thus form'sa cap or hous- I i-ng for the-lower end of the casing. To per- ,mit easy inanipulationof housing B in screwing it into or out of the casing, the base section 9 may be formed with a slightly .pro-

jecting flange or rib 25,- which is easily grasped by the fingers. I

On the ring 10 of member B is mounted an acoustic diaphragm D of proper design and material. There are. many kinds and styles of diaphragms on the-market suitablev for this purpose. The most common material of which these diaphra'gmsare made is mica,-

which is moisture-proof and gives a strong reproduction. Some people, prefer a diaphragm of wood, especially maple, which. gives a more pleasing reproductionthanmica, I

' and operative connections for the. acoustic though perhaps not as strong.

Diaphragm D is'held in place on the ring" 10 in any practical way. In the illustrative embodiment shown ,in the drawings. the supporting ring 10 has an inwardly project- I i ng. shoulder or flange 26 and a screw-thrcaded wall. 27. The diaphragm is clamped firmly in position by a screw-threaded ring '28.

It is preferable to clamp the diaphragm be-" tween a-pair oiwashers 29 of felt, leather,'

rubber, or other sound-absorbing material.

' When the housing or cap-member B is fully screwed into the casing K, the top of ring 10 may rest against a shoulder formed inside the of the rod or wire 37, and-by further calculatcasing, as shown in Fig. l, but this is not .essential when the, diaphragm is held clamped on ring 10 independently of the casing, as by the screw-threaded ring 28. j L

To the ring 10 is fixed a bracket 30 having "0 a pair of spaced lugs 31, between which is pivoted at 32 a lever indicated as a whole by L. This lever is in the form of a bell-crank comprising. a long arm 33 and ashort arm 34.

'The free end of the long arm 33 is rigidly secured to the center of diaphragm D, as indior any other practical means. The point at which the rod 37 is connected to the armature depends upon the amplifying ratio which it is desired to secure between the vibratory movements of the armature and the vibratory movements of the'diaphragm D. By proper.- 1y calculating the distance between the center of the armature and the point of'conne'ction ing the lengths of the arms 33 and 34 of lever L, any desired leverage between the armature and the diaphragm can be secured. These calculations are we rlwithin the skill of the man conversant withthis art. 'i

The operation of my'new telephone re- 'ceiverwill be clear to anyone skilled in the art and I need not, therefore, 0 into any details on this point. It is enOugIi to say that nor? mally the armature Ais held in aneutral'or 1 balanced position between the tips of the pole pieces, as shown in Fig. 2. When a variable current passes through the coil'or coils .21,

the normal magnetic balance of the arma ture is disturbed by the resultant magnetic efiect'of the coils and the'armatu're vibrates in a manner well understood. Th ese. vibrations are in accordance with the current variations in the coil are transmitted in increased ratio through the connections previously described. In this Way, the vibrations of the ai'mature are repeated by the diaphragmin magnified movements, so that the sound produced by'the diaphragm maybe heard at adistance.

.The specific form of magnet construction ing all the operative parts, is insertable into and removable from the base T as a self-contained unit. .As seen in Fig. 1, the opening in the base is sufficiently large to ermit this insertion and removal of the unit '-B with its contained parts. This unit, in the construction shown, is inserted as a whole into the top opening of'the base until the flat annular flange 5'on the upper casing K contacts with the flat annular flange 6 which surrounds the opening in the base. This ready assemblage of the separate parts into an instrument ready for the market, facilitates the manufacturing of the loudspeaker and thus lowers the cost thereof.

It will be understood that changes-and modifications may be made in the various fea tures of my invention without departing from the scope of the appended claims.

This application is a division of my copending case Serial Number 680,597, filed December'14, 1923.

What I claim as my inventon is:

"1. In a loud-speaking telephone receiver, an'outer casing, a unitary support having electromagnetic acoustic mechanism mounted thereon, said support and mechanism constituting a unit insertable into and removable from said casing, a flange on said,

casing, and a stand having an opening surrounded by a shoulder on which said flange- I port are inserted into thestand.

2. In a loudspeaker, a -reproducer unit end and having a sound passage at the other end for connection with an amplifier, a onelece casting removably secured to said housing, said castingcomprising a disk screwed.

into the open end of said housing and a ring Y rigidly c'onne cted to said disk by spaced housing as a unit. 7

posts, a diaphragm supported .on said ring,- and electromagnetic mechanism mounted on said disk for operating said diaphragm said casting and all parts carried thereby being insertable into and removable from said 4. A telephone loudspeaker comprisin a vbase provided at the top with a central tu u-i lar aperture, a reproducer unit consisting of a housing "in which electromagnetic operating mechanism is mounted, said housing having a cylindrical wall adapted to fit snugly into said aperture through the top thereof. and cooperating means on said base and said housing for limiting the inward telescoping movement of the housing on the base, sai reproducer unit bein removable as a whole from. the base throug said aperture.

5. A telephone loudspeaker comprising a base provided at the top with a central tu-.

,said aperture in a tight frictional joint as the housing is forced into the base,- whereby said housing is rigidly supported on said I base without the need of separate fastening means, saidfrictional joint ration of housing and base.

6. A telephone'louds'peaker comprising-a base provided at its upper end'with a cylindrical wallwhichdefines a tubular aperture, said wall terminating in a flat annular shoulder, a reproducer unit consisting of a housing' containing electromagnetic acoustic mechanism, means on. the upper portion of said housing -for connecting the same with an amplifier, said housing having a cylindrical wall of slightly lessdiameter than said tubular aperture, so that said housing wall fits snugly into said aperture into engaging contact with the c lindrical wall of the base, and anannular permitting sepa-' ange on said housing ary ranged to engage 'said shonlder on the base for firmly supporting the reproducer unit on said base, said unit being removable from the base through said aperture 7. A telephone loudspeaker comprising a base having an outwar 1y flaring lower section and an upper section terminating in an opening surrounded'by a flange or shoulder, a casing comprising a closed upper portion and an open lower portion, said upper portion extending above said base and said lower portion projecting through said opening in the base, a screw-threaded section on said lower portion, a neck extending from said upper portion, a horn mounted on said neck, a flange on said casing arranged to engage said base flange, so that said casing is firmly supported on said base, a cap having screwthreads arranged to engage the screw-threads on said casing, said cap and easing forming a housing which constitutes a unit insertable into and removable from saidopening in the base, a-magnet system supported within said housing, and an acoustic diaphragm in said housing and operatively connected with said magnet system. J l

8. In an electromagnetic sound reproducer, a repJroducer unit having an upper casing mem er and a lower casing member separably connected by screw-threaded engagement, said members when assembled forming an enclosing housing with a cylindrical wall, 'e'le'c tromagnetic operating mechanism carried by said lower casing member and removable therewith, an annular flange on said upper casing member, means on said upper memher for supporting an acoustic horn, a supporting base provided at the top with a c lindrical extension projecting axially o the base, said extension defining a tubular aperture into which the cylindrical wall of said housing is adapted to be inserted through the top of the base, the telescoping walls of said housing and said base engaging in a snugfit, and a shoulder on said base arranged to engage said flange on the casing forlimiting the telescoping movement of said houstially above the plane of the lower extremity of said casing, an acoustic horn supported in said cap, a supporting base having a flat cen-' tral apertured portion of a size slightly greater thanzthe diameter of said casing, a

- flat annular flange surrounding said apertured portion, a wall extending outwardly fromsaid flange forming a continuation thereofand comprising said supportingbase and means for securing said unit within; said i apertured portion by a vertically downward movement in which said flat annular flange on said cap contacts with said fiat annular "including a sound reproducer unit comprisnular flange substantially above the plane of flange on said base forming a substantial support for said electromagnetic operating mechanism. Y

10. An electromagneticsound reproducer ing in combination a substantially cup shaped casing, an electromagnetic operating mechanism carried'therein, a screw threaded cap engaging said casing and forming a flat an the lower extremity of said casing, an acoustic horn supported in said cap, a supporting base having a diameter substantially larger than the diameter of said cap in the top thereof and having-walls tapered. to a diameter substantially larger than the diameter of said cap, a flat central apertured portion in the top of said base of a size slightly reaterthan the size of said casing and a flat annular flange formed integral with the wall of said base surrounding saidapertured portion, and means-for securing said'unit Within said apertured portion by a vertically" downward movement in which said flat'annularflange on said cap contacts, with said flat annular flange on said base forming a sub stantial support for said electromagnetic operating mechanism.

' ADOLPHL, THOMAS. 

